As we all know, frequency converters adjust the voltage and frequency of the output power supply by switching their internal IGBTs, providing the required power voltage according to the actual needs of the motor, thereby achieving energy saving and speed regulation. So, what are the methods and measures for frequency converters to protect the motor? Let's take a look together!
1. Overvoltage protection: The inverter output has a voltage detection function, and the inverter can automatically adjust the output voltage to prevent the motor from being subjected to overvoltage and to ensure that the motor operates within the set voltage range.
2. Undervoltage protection: When the motor voltage is lower than 90% of the normal voltage (some are set to 85%), the frequency converter will shut down for protection.
3. Overcurrent protection: When the motor current exceeds 150% of the rated value for 3 seconds, or 200% of the rated current for 10 microseconds, the frequency converter will protect the motor by shutting down.
4. Phase loss protection monitors the output voltage. When a phase is lost, the inverter will alarm and immediately stop to protect the motor.
5. The reverse phase protection inverter can be set so that the motor can only rotate in one direction. The rotation direction cannot be set unless the user changes the phase sequence of the motor's A, B, and C wiring. Otherwise, there is no possibility of reverse phase.
6. Overload protection: The frequency converter monitors the motor current. When the motor current exceeds 120% of the set rated current for 1 minute, the frequency converter will stop the motor to protect it.
7. Grounding Protection: The frequency converter is equipped with a dedicated grounding protection circuit, typically consisting of a grounding protection transformer and a relay. When one or two phases are grounded, the frequency converter immediately shuts down. Of course, if required by the user, we can also design it to immediately shut down upon grounding.
8. Short circuit protection: When the inverter output is short-circuited, it will inevitably cause overcurrent. Within 10 microseconds, the inverter will stop to protect the motor.
9. Overfrequency protection: The inverter has maximum and minimum frequency limiting functions, which ensure that the output frequency can only be within the specified range, thereby realizing the overfrequency protection function.
10. Stall Protection: Stall protection is generally for synchronous motors. For asynchronous motors, stall during acceleration inevitably manifests as overcurrent, which the frequency converter addresses through overcurrent and overload protection. Stall during deceleration can be avoided by setting a safe deceleration time during commissioning.
